Northstar Engines and System Technical Discussion Discussion, Engine crud @ head gasket repair in Cadillac Engine Discussion; Head gaskets/timeserts are being done on my 94 Eldo at 130k miles and the engine is apart on the floor ...

Engine crud @ head gasket repair

Head gaskets/timeserts are being done on my 94 Eldo at 130k miles and the engine is apart on the floor at my mechanic's, so I've had a good look at its guts and have a few questions...(wish I had pics)...
The intake manifolds are about 50 percent filled with dark brown, crusty crud--is this normal and should it be scraped out?
The valves are mostly carbony black except at 2 cylinders where they are powdery white, and, in both cases, many of the valves have a visible thick layer of the respectively colored gunk--normal? Remove it?
The car was throwing off one of the trans solenoid codes (P028) right before I took it in...would it make sense to just replace the solenoids as long as it's just sitting there on the floor waiting for the block to come back with timeserts?
Also, one of the timing chain guides is extremely worn--any reason NOT to replace? Thanks!

Re: Engine crud @ head gasket repair

Are you talking about the phenolic spacer plates between the intake manifold and the cylinder head being full of carbon...???... that is one of the service procedures mentioned frequently on the forum for 93/94 engines...cleaning the carbon out of the EGR passages in the phenolic spacer plates.

Personally, I would leave the valves alone. The deposits come from the heavy ends in the fuel depositing on the hot valves and the deposits will return anyway. Just leave them alone.

Make a picture is possible of what the "extremely worn" timing chain guide looks like. Those rarely if ever need replacing. I suspect you are just seeing the two grooves formed by the timing chain side links. Common and the "wear" stops when the chain rollers reach the surface of the guide.

Re: Engine crud @ head gasket repair

Thanks, Bbob. Yes, those would be the phenolic spacer plates and they are a mess. Would that degree of cloggage be responsible for the knock I heard when occassionally forced to burn regular gas? Or the rare knock I heard once or twice starting up on a hill, even with high test? Should we just soak them in carb cleaner and scrape them out? Is there a case for a totally thorough cleanout, i.e., polishing? Thanks!

Re: Engine crud @ head gasket repair

The spacers are easily cleaned by scraping the grooves out with a screwdriver or similar tool, then wash off with spray brake cleaner or other solvent.

The combustion chamber could be left alone, BUT... I prefer putting the engine back together clean. The chambers are easily cleaned with a little GENTLE scraping and a brass cleaning brush. I mean you have to get the head surface clean for the gasket, so it seems silly to leave the carbon buildup in the chambers.

As for the port side of the valves, if you decide to clean them, I would tip the head and flush the port with spray brake cleaner just to remove the excess deposits, I would not do any scraping on this area.

Re: Engine crud @ head gasket repair

Finally got some pics of this engine apart--more to follow. Last one is the mess apart on the floor; first couple are the cylinder banks with the gaskets on the floor; I think the phenolic spacer plates are being cleaned; that's the tranny in the foreground; the block's being timeserted somewhere off-site. Intersting to look inside a 10 y.o. engine with 130k miles, fairly poorly maintained, I'm now guessing...

Re: Engine crud @ head gasket repair

Looks pretty normal to me? In that first pic, the cylinder on the far right looks a little oily/wet. Were you experiencing blue smoke on startup? Or was that the cylinder where the headgasket leak occured?

Re: Engine crud @ head gasket repair

No smoke, blue or white and unfortunately, never did cylinder by cylinder compression check so don't know where the offenders were. A couple of the head bolts were extremely loose on disassembly...and that gasket on the floor in that first pic looks especially corroded (if the orientation is correct). I'm also attaching a shot of the timing chain guide that the mechanics are worried about ("it's down to metal"). The engine was making a distinctive, constant, mild 'metal on metal' sound that I could not pinpoint with Bbob's hose-a-scope. So, I'm wondering (a) if these worn guides would generate a mild grating noise and (b)do they need replacing? Many thanks to all viewing and responding!

Re: Engine crud @ head gasket repair

Here's one more pic of the engine side of the firewall--the mechanic thinks the slits in the insulation might be there from replacement of the condenser (sorry, evaporator)...make sense to anyone? Remember, we found some very odd bolts missing deep within the engine cradle on disassembly and are theorizing that it was taken apart once before and haphazardly put back together...but for what reason?...

Re: Engine crud @ head gasket repair

Originally Posted by RLLOVETT

No smoke, blue or white and unfortunately, never did cylinder by cylinder compression check so don't know where the offenders were. A couple of the head bolts were extremely loose on disassembly...and that gasket on the floor in that first pic looks especially corroded (if the orientation is correct). I'm also attaching a shot of the timing chain guide that the mechanics are worried about ("it's down to metal"). The engine was making a distinctive, constant, mild 'metal on metal' sound that I could not pinpoint with Bbob's hose-a-scope. So, I'm wondering (a) if these worn guides would generate a mild grating noise and (b)do they need replacing? Many thanks to all viewing and responding!

Are you sure the guide is worn thru to the metal...???

It looks like most guides do...."marked" by the chain side links (those are the two grooves) with a light coating of varnish from age and heat. The guide will look like it is to the metal in the grooves but I would be amazed if it is. I have seen some very high mile guides and never seen one wear thru to the metal backing. Just the grooves form and they stay that way.

Re: Engine crud @ head gasket repair

I'll advise my guys to ignore them...especially since I found out today they're ordering all the parts from the local Caddy dealer...I'm praying they get a wholesale price on them cuz I know there are better parts prices for me online...Was told the dealer keeps a list of 'what they'd need' for the head gasket repair so maybe they'll get most of what they need to put it back together. Thanks again for the input!

Re: Engine crud @ head gasket repair

Well, I wouldn't ignore them. It only takes a moment to look at the part and see if you can actually see metal at the bottom of the grooves or not. Possibly they are worn, who knows. I can only relate past experience, not see your parts in person.... The info provided is to help you inspect the parts from a knowlegeable standpoint...not just ignore the parts...

Re: Engine crud @ head gasket repair

Point taken...there was metal showing through, making the mechanics nervous, so I told them to replace if they felt necessary. They're reassembling today so I' hoping to have the car back no later than Monday...say a prayer to the gods of electronics that that part goes uneventfully...

Re: Engine crud @ head gasket repair

Originally Posted by RLLOVETT

Point taken...there was metal showing through, making the mechanics nervous, so I told them to replace if they felt necessary. They're reassembling today so I' hoping to have the car back no later than Monday...say a prayer to the gods of electronics that that part goes uneventfully...

From the picture it doesn't look like metal is showing thru at the bottom of the grooves where the chain links "cut" the nylon wear surface. Where was "metal" showing thru?? Otherwise, that is how the guides are supposed to look after the engine was run.

Re: Engine crud @ head gasket repair

Unfortunately, my motor is still in parts on the floor, so I had another chance to inspect those guides and they are, in fact, nicely slotted and NOT worn to metal. The block is back (wrapped in plastic) and the OEM parts are in boxes and bags on the floor...the service manager is going to try to pull a few strings with the car rental co. (Enterprise) to help me out with the delay...but my wife is ready to shoot me...Saturday will be the beginning of week3 without the car...just ventilating, thanks!

Re: Engine crud @ head gasket repair

Paid a visit to the patient today...the timing chain guide that was troubling them was NOT the one I photod. It was the one that lives right next to the timing drive gear in the central part of the engine, and it was down to bare metal, to the point where the short chain it guides was worn on the lower half of the 'rivets' (?) that hold the links together. They're replacing both the guide and the chain (Caddy dealer said they'd never heard of one of these chains replaced...). They're also replacing the drive gear itself out of concern for the excessive play between it and the shaft it lives on...the interior surface of the gear had a palpable lip at its end where it was unworn...the good news is the guy who's working on it is doing a fussy job of cleaning all the surfaces and assuring things fit. "You'll be driving it tomorrow." LOL and how!